In a recent article on peony pollen size and shape there was a listing of some cultivars with their ploidy level. There were some surprises:

I did not expect Old Faithful to be triploid for example, I always assumed it was tetraploid. The surefire way to know whether a cultivar is di-,-tri-, tetraploid is counting chromosomes of course, but that is unfortunately something I don’t have the knowledge for. Sometimes people say they know by the look a plant what it is? I’d be much interested to hear what one has to look for then or if somebody has lists of cultivars that are surely tetraploid. For nearly all species ploidy level is known, so often from crosses between them, it can be deduced what ploidy level the seedlings will have. But when it comes to those ‘advanced generation hybrids’ it’s a bit more difficult, especially when the parentage is unknown.

As it is assumed that both diploid and tetraploid pollen has more viable grains and crossing between diploid-diploid, tetra-tetra and diploid-tetra gives more seeds, it is a least interesting to know. I have spent many, many hours crossing hundreds of flowers from some cultivars to end up with not a single seed, so I would be nice to be able to direct the time we have to somewhat more “fruitful” crosses 😉